It is well known in the automotive mirror art to provide a powerfold exterior rearview mirror assembly on a vehicle wherein a head portion or movable portion of the mirror assembly may be pivotable via a motor or power pack or actuator or the like, such that the movable portion or head portion may be pivoted about a generally vertical pivot axis relative to a sail or base or fixed portion of the mirror assembly. It is desirable to tightly secure or attach or affix the movable head portion to the powerfold motor power pack or unit to minimize vibration between the head portion and the base portion of the exterior rearview mirror assembly. As the size of the exterior mirror assemblies increases, there are greater concerns that the head portion may vibrate relative to the base portion.